count-circle-sides.py

import argparse

from PIL import Image


white = 255
black = 0

parser = argparse.ArgumentParser()
parser.add_argument('image', help="image to load")
file_name = parser.parse_args().image

img = Image.open(file_name).convert(mode='L')
px = img.load()

sides = 0

for i in range(img.size[0]):
    for j in range(img.size[1]):
        if px[i,j] == white:
            try:
                if px[i-1,j] == black:
                    sides += 1
            except IndexError:
                pass

            try:
                if px[i,j-1] == black:
                    sides += 1
            except IndexError:
                pass

            try:
                if px[i+1,j] == black:
                    sides += 1
            except IndexError:
                pass

            try:
                if px[i,j+1] == black:
                    sides += 1
            except IndexError:
                pass

print(sides)